The next CAARC General Meeting will be held on Wednesday May 18th. at 7.30PM We will meet at the new Red Deer County Protective Services Station Number 6 building located at 249 Clearview Drive east of the Westerner Park. Go south of 19th Street on 40th Ave . Turn left on Clearview Drive and follow it to the east around the corner south to the Red Deer County Protective Services Station Number 6 Building on the east side.
Super Rock Mite 40m CW QRP XCVR
I bought this kit for US$16 including postage. It features a keyer and substantial output power (see below). I am posting some of the documentation inconsistencies that I found – hopefully this will smooth the build for others. I bought my kit here http://www.banggood.com/DIY-51-Super-Rock-Mite-RM-Kit-CW-Transceiver-Shortwave-Telegraph-p-991246.html
Clarification to Bill of Materials (list of components)
- C22 to C34 0.1 uF (104) disc capacitors. Approximately half of these capacitors tested within 20% of designated value, the rest within 50% of designated value. One capacitor was 0.028 uF. All these capacitors were replaced with quality ceramic components testing within 10% or better of designated value.
- C25 and C26: these are apparently the same capacitor. Documentation inconsistency between versions?
- C13 to C21: 0.01 uF (103) disc capacitors. Less than half were within 20% so I replaced them all with good ceramic capacitors.
- C35: 470 pF is necessary to prevent oscillation in the NE5532. Put it in.
- Install the 100 pF capacitor located on the edge of the board between W2 and U3.
- Y1, Y2, Y3: I used DIP header pins on the board and soldered the crystals to DIP sockets. Cut strips of 3 pins each and remove the center pin for the header on the board. This arrangement will permit you to QSY to 7.030 / 7.040 when you find some appropriate crystals. I found 7.0375 crystals in the same holder at US$0.10 each from Tayda Electronics and they should arrive in the mail any day now. The pins will also let you painlessly try the VFO/DDS mod as per the March 2016 QST article pp 39-44.
- R2, R3: The schematic states that 1 W resistors should be used however 1/4W resistors are supplied. R3 is in series with the emitter lead of the 8050 driver transistor. I looked up the specs on this transistor and it can handle sufficient current to fry a ¼ W resistor. I didn’t have a 1 W 22 ohm resistor in my parts so I used a 2W resistor. It protrudes a bit but fits. DO NOT use a wire wound resistor for R3 . I check inductance of the resistor before using it. For R2 I found a 1/2W 22 ohm resistor to substitute but I am not convinced it is necessary.
- Electrolytic capacitors: The BoM shows 16V electrolytics. My kit supplied 25V capacitors. I strongly recommend that you do not use 16V units with a 12V (13.6V) supply.
- D3: I have used the 1N4001 as a varicap however I also once wasted several hours troubleshooting because a 1N4001 diode somehow prevented crystal oscillation. I found that a BB221 varicap works well so that is what I used.
- L1 and L2: My toroid calculator gives a value of 1 uH for 16 turns on a T37-2 form. The photo in the Engrish instructions shows 17 turns. The LPF is not working well for me as I am seeing a drop of about 12 V P-P between the input and output sides of the filter section. I used tested capacitors, within 2% of given value, in the filter. If anyone knows how to calculate the optimum values for L1, L2 please send me an email (QRZ.com).
- Q2 output transistor. I cut a mica power transistor insulator to fit under the heat sink and superglued it in place. The solder resist under the heat sink is a good insulator but …
- LEDs: the long lead goes into the square pad. I used the green LED for receive and the red LED for transmit.
- For the initial smoke test, after connecting a dummy load to the antenna terminals, I put a 10 ohm 5W resistor in series with the supply. Current draw through the 10 ohm resistor was 85 mA.
- I am getting 1.1 watts out into a calibrated watt meter using a 12 V battery as a supply. As mentioned above, there is definitely a problem with my LPF. Once I get the LPF issue sorted out and up the supply voltage from my 13.6V buss, I expect to see several watts RMS out.
- I used a USB to RS232 cable to connect the Rock Mite to my computer after finding the English version of the software. The software definitely does something but needs further research. Who designs a board with an RS232 interface in 2016? I was lucky my patch cable worked.
On the air: I received reports of clean keying from several hams within 100Km. A CQ in the evening brought a prompt response from Europe. The QSK works fine. My straight key was recognized after sending a few V’s. The side tone leaves room for improvement. I connected the audio out through a small digital audio amplifier module. I am confident that a good CW operator could fill his logbook using this transceiver. For the rest of us I suggest working stations within a few hundred Km during daylight hours – the large number of stations heard concurrently after dark overwhelm my ability to sort out signals by tone.
The PCB layout shows some thought and some nice features. It was designed without mounting holes made to slide into a ready-made case. As may be seen on the photos I had a groove machined into some aluminum bar stock to hold the PCB.
This kit fails its “ISO9002 audit” because of the “instructions” and the poor quality of the disc capacitors supplied. Google does a terrible job translating Mandarin to English.
We have noticed that there are a lot of members who have not paid their annual membership dues over the last couple of years. Please help keep your repeaters and club active by submitting your membership dues at the Picnic or the November meeting. You can also download the CAARC membership and renewal form under the “Site tools” tab and send your dues by snail mail to the listed address on the bottom of the form or bring it to the meeting. Your support helps keep your repeaters operating and your club active.
Thankyou from your executive
73 CAARC Executive
We have a new volunteer for the Monday evening net controller.
Thanks to Maria VA6TFL for your willingness to help with the net.
Any other volunteers would be welcomed to add to the list.
Thanks to the five other net controllers for taking your turn.
Please check Updated Net Controller List under the Net info TAB
CAARC Net Controller Co-ordinator
CANWARN, acronym for CANadian Weather Amateur Radio Network
Please note that CANWARN is not about storm chasing, it is about putting trained eyes at the local level to confirm what is happening under severe weather and communicating that information to the Meteorological Service of Canada.Here’s how CANWARN works in Central Alberta. When the regional weather forecast office (for the prairies this is the Prairie Storm Prediction Centre in Winnipeg, MB) would like to get ground observations of potentially severe thunderstorms they telephone the CANWARN person whom they have listed as the call-out person for the area of interest. In Central Alberta this will be the same people that are listed as ARES emergency coordinators. All Central Alberta and Olds ARES EC’s are trained CANWARN network controllers. The mechanics of how the net operates, local hams are notified and how their weather reports are forwarded to the forecast office are up to the CANWARN net controller. CANWARN Net Control may relay the observations or may elect to use a phone to put the forecasters and amateur observer in direct contact.Typically, the person contacted by the Meteorological Service of Canada notifies the affected-area CANWARN hams who then radio their weather reports to their CANWARN Net Control Net. Net control then forwards the weather observations to the weather forecast office on a dedicated 1-800 phone number. As the storm moves along, reports would hopefully still come in from either stationary or mobile spotters allowing weather forecasters to continually compare the Carvel and Strathmore Doppler radar to what is being observed at ground level (below the radar horizon) and adjust their weather forecasts, Watches and Warnings accordingly.
If you are interested in attending a CANWARN training session at the Red Deer Picnic in June please email VE6CIA Garry
ve6cia at gmail.com
to be included in the list.
An informative article on specifications for coaxial cable. Download the article by clicking on the link below.
A newer version of the instructions incorporating corrections and suggestions from proof readers. Thanks to K9HZ, KE7HR and ON7AN for their help with this project. Any errors are mine. Use at your own risk. Comments, corrections and suggestions most welcome.
Good luck with your build.
I just finished building this kit that I bought online (link above). In my opinion it meets the main requirements of a kit for hams: 1) cheap 2) fun to build 3) it actually works.
So what’s the catch? The instructions are either in Mandarin Chinese or in Google Translate English. Amusing to read but difficult to follow. So with lots of cogitation, head scratching, questions to several other hams, and the assistance of the boffins at Bletchley Park we are offering CAARC website readers a decrypted version of the kit instructions.
The first paragraphs are given below as a “teaser”.
These instructions are my attempt to put the “manual” supplied for download on the seller’s website into more conventional English. They are based primarily on the “RF‐AMP‐2078 debug instructor V303” (sic) downloaded from the website. You will note that the schematic is dated 5 August, the BoM sometime in September and the PCB is marked “20151229”. I found more than a dozen inconsistencies in values and markings between the PCB and the documents. Also there appear to be several “typos” on the PCB silk screening. I have endeavored to sort this out and update my documentation to match the PCB supplied with the kit.
It is no doubt feasible for an experienced builder to successfully assemble the kit using only the schematic and the silk screening on the PCB. My objective is to make this inexpensive kit available to a wider audience of radio amateurs, who may feel less confident about building their first MOFET PA without some additional guidance. Anyone who does not have previous experience soldering the small SMD parts used in this kit is advised to practice first.
A pdf file with the complete instructions will be linked to this post within the next few days. Watch this space.